LIN28 promotes tumorigenesis in colorectal cancer but is not associated with metastatic spread.

BACKGROUND: Tumor stem cells play a role in metastatic spread in colorectal cancer (CRC). The oncogene LIN28A/B, a prognostic marker in CRC, is involved in tumorigenesis and maintains stem cell function. Therefore, it was the aim of the present study to clarify whether LIN28A/B is involved in metastatic spread in CRC. METHODS: Expression of LIN28A/B was analyzed in patients with colon adenocarcinoma in a matched case-control study comparing patients with corresponding liver metastases (n = 42) and patients without hepatic spread within five years (n = 42) by applying immunohistochemistry. Further, LIN28A/B expression was correlated with stem cell associated markers (SOX2, CD133). RESULTS: LIN28A and B expression significantly correlated with SOX2 expression (p = .02, and p = .04 respectively) but not with CD133 expression. This correlation between LIN28 A/B and SOX2 was not reflected in differences in hepatic spread. In this respect, there was no significant association between LIN28A/B expression and liver metastases. CONCLUSION: LIN28A/B might be involved in tumor initiation and progression in CRC but is not associated with hepatic spread.

Biomarker alterations associated with distinct patterns of metastatic spread in colorectal cancer.

Metastatic spread is the most important life-threatening feature of colorectal cancer and is supposed to be mainly driven by alterations in different carcinogenic pathways. The present study compared mutation and expression profiles of distinctive biomarkers in colorectal cancer patients with different clinical metastatic patterns. As for a case-control study, patients were matched according to T category, grading and primary tumour site. Overall, 246 patients with either exclusive lung metastasis (N = 82), exclusive liver metastasis (N = 82) or non-metastatic colorectal cancer (N = 82) were identified. Paraffin-embedded specimens were examined for mutations in the RAS and RAF genes and for the expression of ß-catenin and CD133. Clinical endpoints were presence or absence of distant metastasis, formation of metastasis in lungs versus the liver and survival. MAPK pathway mutations in either the KRAS, NRAS or BRAF gene were associated with the development of lung metastasis (63.4%) compared to the control group (47.6%; p = 0.04). MAPK pathway alterations plus high ß-catenin expression were associated with metastasis to the lungs but not to the liver (28.0% vs. 13.4%; p = 0.02). High CD133 expression correlated with the development of liver metastasis compared to the control group (30.5% vs. 14.6%; p = 0.02). This data indicates that different patterns of distant spread are associated with specific biomarker alterations and may represent different molecular subtypes of colorectal cancer. However, underlying mechanisms of metastasis formation in different anatomic sites remains unclear. Since knowledge of the anticipated site of distant spread would substantially impact clinical management, further research is needed to identify solid biomarkers for different metastatic patterns.

Correction to: The natural course of pT2 prostate cancer with positive surgical margin: predicting biochemical recurrence.

In multivariate analysis, GS of the regular prostatectomy specimen was the only statistically significant parameter for pT2R1 prostate cancer.

[Status of the availability and use of next generation sequencing (NGS) in bladder cancer-a questionnaire within the uropathology working group]. / Status der Verfügbarkeit und Anwendung von "next generation sequencing" (NGS) beim Harnblasenkarzinom ­ eine Umfrage in der Arbeitsgemeinschaft Uropathologie.

BACKGROUND: Technical advancement and availability of high-throughput analysis has advanced molecular subtyping of most cancers. Thus, new possibilities for precision oncology have emerged. AIM: Therefore, we aimed to collect data regarding availability and use of next generation sequencing (NGS) for urothelial cancer within the uropathology working group of the German Society of Pathology. METHODS: We collected data by questionnaires and additionally asked for sequencing results of bladder cancers in the participating institutions. RESULTS: A total of 13 university-affiliated institutes of pathology took part in the survey. All university institutes offer NGS-based molecular panel diagnostics and provide panels covering between 15 and 170 genes. Altogether, only 20 bladder cancers were sequenced in routine diagnostics and for 10 cancers potential targeted treatment options were available. DISCUSSION: So far, despite availability of NGS diagnostics at university institutes of pathology, only few bladder cancer samples have been sequenced. Based on current data from the molecular subtyping of bladder cancers, we recommend a step-by-step protocol with basic immunohistochemistry analysis and subsequent subtype-dependent analyses, e.g., alterations of the fibroblast growth factor receptors (FGFR) or comprehensive gene panel analyses.

Consensus molecular subgroups (CMS) of colorectal cancer (CRC) and first-line efficacy of FOLFIRI plus cetuximab or bevacizumab in the FIRE3 (AIO KRK-0306) trial.

BACKGROUND: FIRE-3 compared first-line therapy with FOLFIRI plus either cetuximab or bevacizumab in 592 KRAS exon 2 wild-type metastatic colorectal cancer (mCRC) patients. The consensus molecular subgroups (CMS) are grouping CRC samples according to their gene-signature in four different subtypes. Relevance of CMS for the treatment of mCRC has yet to be defined. PATIENTS AND METHODS: In this exploratory analysis, patients were grouped according to the previously published tumor CRC-CMSs. Objective response rates (ORR) were compared using chi-square test. Overall survival (OS) and progression-free survival (PFS) times were compared using Kaplan-Meier estimation, log-rank tests. Hazard ratios (HR) were estimated according to the Cox proportional hazard method. RESULTS: CMS classification could be determined in 438 out of 514 specimens available from the intent-to-treat (ITT) population (n = 592). Frequencies for the remaining 438 samples were as follows: CMS1 (14%), CMS2 (37%), CMS3 (15%), CMS4 (34%). For the 315 RAS wild-type tumors, frequencies were as follows: CMS1 (12%), CMS2 (41%), CMS3 (11%), CMS4 (34%). CMS distribution in right- versus (vs) left-sided primary tumors was as follows: CMS1 (27% versus 11%), CMS2 (28% versus 45%), CMS3 (10% versus 12%), CMS4 (35% versus 32%). Independent of the treatment, CMS was a strong prognostic factor for ORR (P = 0.051), PFS (P < 0.001), and OS (P < 0.001). Within the RAS wild-type population, OS observed in CMS4 significantly favored FOLFIRI cetuximab over FOLFIRI bevacizumab. In CMS3, OS showed a trend in favor of the cetuximab arm, while OS was comparable in CMS1 and CMS2, independent of targeted therapy. CONCLUSIONS: CMS classification is prognostic for mCRC. Prolonged OS induced by FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab in the FIRE-3 study appears to be driven by CMS3 and CMS4. CMS classification provides deeper insights into the biology to CRC, but at present time has no direct impact on clinical decision-making.The FIRE-3 (AIO KRK-0306) study had been registered at ClinicalTrials.gov: NCT00433927.

GABA and glutamate moderate beta-amyloid related functional connectivity in cognitively unimpaired old-aged adults.

BACKGROUND: Effects of beta-amyloid accumulation on neuronal function precede the clinical manifestation of Alzheimer's disease (AD) by years and affect distinct cognitive brain networks. As previous studies suggest a link between beta-amyloid and dysregulation of excitatory and inhibitory neurotransmitters, we aimed to investigate the impact of GABA and glutamate on beta-amyloid related functional connectivity. METHODS: 29 cognitively unimpaired old-aged adults (age = 70.03 ±â€¯5.77 years) were administered 11C-Pittsburgh Compound B (PiB) positron-emission tomography (PET), and MRI at 7 Tesla (7T) including blood oxygen level dependent (BOLD) functional MRI (fMRI) at rest for measuring static and dynamic functional connectivity. An advanced 7T MR spectroscopic imaging (MRSI) sequence based on the free induction decay acquisition localized by outer volume suppression' (FIDLOVS) technology was used for gray matter specific measures of GABA and glutamate in the posterior cingulate and precuneus (PCP) region. RESULTS: GABA and glutamate MR-spectra indicated significantly higher levels in gray matter than in white matter. A global effect of beta-amyloid on functional connectivity in the frontal, occipital and inferior temporal lobes was observable. Interactive effects of beta-amyloid with gray matter GABA displayed positive PCP connectivity to the frontomedial regions, and the interaction of beta-amyloid with gray matter glutamate indicated positive PCP connectivity to frontal and cerebellar regions. Furthermore, decreased whole-brain but increased fronto-occipital and temporo-parietal dynamic connectivity was found, when GABA interacted with regional beta-amyloid deposits in the amygdala, frontal lobe, hippocampus, insula and striatum. CONCLUSIONS: GABA, and less so glutamate, may moderate beta-amyloid related functional connectivity. Additional research is needed to better characterize their interaction and potential impact on AD.

Neurotrophic tropomyosin receptor kinase (NTRK) and nerve growth factor (NGF) are not expressed in Caucasian patients with biliary tract cancers: pooled data from three independent cohorts.

BACKGROUND: Neuronal signaling has been implicated in the pathophysiology of multiple malignancies. In biliary tract cancers (BTCs), tumor cell expression of nerve growth factor (NGF) and its receptor neurotrophic tropomyosin receptor kinase (NTRK) has been reported in Asian patients and linked to inferior clinical outcome. Furthermore, NTRK fusions have emerged as a promising target in various cancers. Expression patterns of these markers in Caucasian patients remain unknown. METHODS: In this study, 106 patients with BTCs were included. Immunohistochemistry for pan-NTRK and NGF-beta was performed on > 90 samples of this cohort. Additionally, samples from two independent cohorts, incorporating 254 cases, were used to confirm the findings of the original cohort. RESULTS: While expression of pan-NTRK and NGF-beta was readily detectable in peri-tumoral nerves, these markers were not detectable in malignant epithelial cells in our cohort. CONCLUSIONS: In a large cohort of Caucasian patients with BTC, NTRK and NGF-beta were not detectable, underscoring potential differences between Caucasian and Asian patient populations.

Comparison of health-related quality of life after transarterial chemoembolization and transarterial radioembolization in patients with unresectable hepatocellular carcinoma.

PURPOSE: The purpose of this study was to compare quality of life (QoL) after two different transarterial therapies [transarterial chemoembolization (TACE) and transarterial radioembolization (TARE)] for patients with unresectable hepatocellular carcinoma (HCC) to assess tumor therapy in palliative situation additional to traditional aims like survival or image response. MATERIAL AND METHODS: QoL was evaluated with two validated questionnaires (EORTC QLQ-30 and EORTC HCC18) before and 14d after treatment in 94 initial therapies (TACE n = 67; TARE n = 27). QoL changes after treatment were analyzed. Tumor response was evaluated using RECIST/WHO/mRECIST/EASL criteria. A multivariate linear regression was undertaken to identify potential influence factors on change of QoL. RESULTS: Mean return rate of questionnaires was 71.3% allowing analysis of 67 therapies (TACE n = 46; TARE n = 21). Initial global health status/QoL was significantly higher in TACE (62.5%) compared to TARE with 50.8%. Absolute global health decrease was higher in TACE (- 10.5%) compared to TARE (- 4.8%, p = 0.396). Also relative global health decrease was higher in TACE (- 16.82%) compared to TARE (- 9.37%). Findings for other items were corresponding, as less impairment was found for TARE compared to TACE for physical/social functioning, fatigue and pain. Objective mRECIST response rate was 22.8% in TACE and 21.1% in TARE. CONCLUSION: Neither TACE nor TARE showed a major decrease in QoL after first treatment. TACE showed a slightly but not significantly higher decrease, so this study is not clearly in favor for one treatment. But with the addition that TARE showed less decrease even in patients with higher tumor burden and lower baseline.

Repeated mutKRAS ctDNA measurements represent a novel and promising tool for early response prediction and therapy monitoring in advanced pancreatic cancer.

Background: The presence of mutated KRAS (mutKRAS ctDNA) in plasma samples has been consistently shown to be a negative prognostic indicator in pancreatic cancer (PC). Only small pilot studies have evaluated the value of serial mutKRAS ctDNA-measurements in PC. Patients and methods: The aim of the present study was to explore the potential of repeated mutKRAS ctDNA measurements for response prediction and therapy monitoring in advanced PC patients. We used the BEAMing technology to determine levels of mutKRAS ctDNA, CA 19-9, CEA and CYFRA 21-1 in 284 plasma samples of 54 patients with advanced PC receiving gemcitabine-based chemotherapy. Absolute levels and kinetics of mutKRAS ctDNA, CA 19-9, CEA and CYFRA 21-1 were correlated to radiological response, progression-free and overall survival. Results: mutKRAS ctDNA was present in a majority of advanced PC patients (n = 36/54, 67%) and indicated tissue KRAS mutation status with a high sensitivity (75%) and specificity (100%). The presence of mutKRAS ctDNA, as well as higher levels of CA 19-9, CEA and CYFRA 21-1 before initiation of the first-line chemotherapy, was significantly correlated to an adverse overall survival. During therapy, changes in mutKRAS ctDNA levels were more rapid and pronounced than changes in protein-based tumor markers. A decrease in mutKRAS ctDNA levels during therapy was an early indicator of response to therapy, while there was no significant correlation between kinetics of CA 19-9, CEA or CYFRA 21-1 and response to chemotherapy during the first four weeks of treatment. Repeated mutKRAS ctDNA measurements during follow-up appeared to be superior to protein-based tumor markers in detecting progressive disease (sensitivity: 83%, specificity: 100%). Conclusion: mutKRAS ctDNA kinetics appear to be a powerful and highly specific tool in early response prediction and therapy monitoring of advanced PC patients receiving chemotherapy.

Ecological momentary assessment of contextual variables, satisfaction, and emotional and behavioral states of adolescents by level of victimization.

The harmful effects of victimization on mental health have been demonstrated in several age groups, cultures, and populations, but there is wide variability in the resulting psychopathology. Ecological momentary assessment (EMA) allows the expression of an emotional state to be recorded at any given time and linked to a situation or context. This study aimed to analyze the contextual variables (where, with whom, and what), momentary satisfaction, and perception of momentary emotional and behavioral symptoms in a cohort of adolescents by the level of victimization, using EMA. We explored the everyday symptom profiles and the contexts in which events took place among 100 adolescents over a one-week period. Sociodemographic data were collected and assessment was done using the EMA (as a smartphone application) and the Juvenile Victimization Questionnaire (to assess childhood and adolescent victimization). In this study, regarding contextual variables, the group with the highest level of victimization (top 10%) showed a significant relationship with being away from home and being with friends other than classmates, and not being with parents or relatives. There was also an unexpectedly higher frequency of sporting engagement in this group. A relationship existed between emotional and behavioral problems and higher levels of victimization. In conclusion, the different groups of victimized subjects present a relatively high level of satisfaction in relation to the daily contexts and show low levels of emotional and behavioral symptomatology.

Multicenter validation of cancer gene panel-based next-generation sequencing for translational research and molecular diagnostics.

The simultaneous detection of multiple somatic mutations in the context of molecular diagnostics of cancer is frequently performed by means of amplicon-based targeted next-generation sequencing (NGS). However, only few studies are available comparing multicenter testing of different NGS platforms and gene panels. Therefore, seven partner sites of the German Cancer Consortium (DKTK) performed a multicenter interlaboratory trial for targeted NGS using the same formalin-fixed, paraffin-embedded (FFPE) specimen of molecularly pre-characterized tumors (n = 15; each n = 5 cases of Breast, Lung, and Colon carcinoma) and a colorectal cancer cell line DNA dilution series. Detailed information regarding pre-characterized mutations was not disclosed to the partners. Commercially available and custom-designed cancer gene panels were used for library preparation and subsequent sequencing on several devices of two NGS different platforms. For every case, centrally extracted DNA and FFPE tissue sections for local processing were delivered to each partner site to be sequenced with the commercial gene panel and local bioinformatics. For cancer-specific panel-based sequencing, only centrally extracted DNA was analyzed at seven sequencing sites. Subsequently, local data were compiled and bioinformatics was performed centrally. We were able to demonstrate that all pre-characterized mutations were re-identified correctly, irrespective of NGS platform or gene panel used. However, locally processed FFPE tissue sections disclosed that the DNA extraction method can affect the detection of mutations with a trend in favor of magnetic bead-based DNA extraction methods. In conclusion, targeted NGS is a very robust method for simultaneous detection of various mutations in FFPE tissue specimens if certain pre-analytical conditions are carefully considered.

Impact of BRAF and RAS mutations on first-line efficacy of FOLFIRI plus cetuximab versus FOLFIRI plus bevacizumab: analysis of the FIRE-3 (AIO KRK-0306) study.

BACKGROUND: RAS and BRAF mutations have been identified as negative prognostic factors in metastatic colorectal cancer. Efficacy of 5-fluorouracil, leucovorin, irinotecan (FOLFIRI) plus bevacizumab in patients with RAS-mutant tumours needs to be further evaluated. Whether to treat patients with BRAF-mutant tumours with either bevacizumab or anti-epidermal growth factor receptor (EGFR) antibodies remains unclear. METHODS: Patients treated within the FIRE-3 trial were retrospectively tested for BRAF and RAS mutations using formalin fixated paraffin embedded (FFPE) tumour material applying pyrosequencing for KRAS and NRAS exon 2, 3 and 4 mutations as far as for BRAF mutations. Survival analysis was done using Kaplan-Meier estimation and differences were expressed using the log-rank test. Overall response rate (ORR) was compared using Fisher's exact test. Data from a central independent radiological response evaluation were used to calculate early tumour shrinkage (ETS) and depth of response (DpR). RESULTS: Overall, 188 patients with RAS-mutant tumours and 48 with BRAF-mutant tumours were identified. In BRAF-mutant patients, ORR was numerically higher in the cetuximab versus the bevacizumab arm (52% versus 40%), while comparable results were achieved for progression-free survival (PFS; hazard ratio [HR] = 0.84, p = 0.56) and overall survival (OS; HR 0.79, p = 0.45). RAS mutation was associated with a trend towards lower ORR (37% versus 50.5%, p = 0.11) and shorter PFS (7.4 versus 9.7 months; HR 1.25; p = 0.14) in patients receiving FOLFIRI plus cetuximab versus bevacizumab, but OS was comparable (19.1 versus 20.1 months; HR 1.05; p = 0.73), respectively. ETS identified subgroups sensitive to cetuximab-based treatment in both BRAF- (9/17) and RAS-mutant (18/48) patients and was associated with significantly longer OS. DpR was comparable between both treatment arms in RAS- and BRAF-mutant patients, respectively. CONCLUSIONS: In BRAF- and RAS-mutant patients, cetuximab- and bevacizumab-based treatment had comparable survival times. ETS represents an early parameter associated with the benefit from anti-EGFR, while this was not the case with vascular endothelial growth factor A blockade.

[Neuroendocrine neoplasia of the stomach : What is new?] / Neuroendokrine Neoplasien des Magens : Was ist neu?

INTRODUCTION: Neuroendocrine Neoplasms are classified according to the new WHO classification in (1.) well differentiated neuroendocrine tumors G1 (NET G1, Ki67 ≤ 2 or mitosis count <2) and (2.) well differentiated neuroendocrine tumors G2 (NET G2, Ki67 3-20 or mitosis count 2-20) and (3.) poorly differentiated neuroendocrine carcinomas G3 (NEC G3, Ki67 > 20 or mitosis count >20). MATERIAL AND METHODS: In this study 310 NENs of the Ludwig-Maximilians-University in Munich were reevaluated according to the new WHO classification. RESULTS: 7% of the analyzed NENs were presented as neoplasias of the stomach. In NENs of the stomach three distinct subtypes are recognized: (1) type 1 associated with autoimmune chronic atrophic gastritis (2) type 2, associated with multiple endocrine neoplasia (MEN1) and Zollinger-Ellison Syndrom; and (3) type 3, sporadic tumors. DISCUSSION: Precursor lesions (i. e. hyperplasia of the ECL cells) are found in patients with hypergastrinaemia (type 1 and 2). This article should provide insights into the diagnosis of NENs of the stomach with emphasis on the new international standard.

EWS-FLI1-mediated suppression of the RAS-antagonist Sprouty 1 (SPRY1) confers aggressiveness to Ewing sarcoma.

Ewing sarcoma is characterized by chromosomal translocations fusing the EWS gene with various members of the ETS family of transcription factors, most commonly FLI1. EWS-FLI1 is an aberrant transcription factor driving Ewing sarcoma tumorigenesis by either transcriptionally inducing or repressing specific target genes. Herein, we showed that Sprouty 1 (SPRY1), which is a physiological negative feedback inhibitor downstream of fibroblast growth factor (FGF) receptors (FGFRs) and other RAS-activating receptors, is an EWS-FLI1 repressed gene. EWS-FLI1 knockdown specifically increased the expression of SPRY1, while other Sprouty family members remained unaffected. Analysis of SPRY1 expression in a panel of Ewing sarcoma cells showed that SPRY1 was not expressed in Ewing sarcoma cell lines, suggesting that it could act as a tumor suppressor gene in these cells. In agreement, induction of SPRY1 in three different Ewing sarcoma cell lines functionally impaired proliferation, clonogenic growth and migration. In addition, SPRY1 expression inhibited extracellular signal-related kinase/mitogen-activated protein kinase (MAPK) signaling induced by serum and basic FGF (bFGF). Moreover, treatment of Ewing sarcoma cells with the potent FGFR inhibitor PD-173074 reduced bFGF-induced proliferation, colony formation and in vivo tumor growth in a dose-dependent manner, thus mimicking SPRY1 activity in Ewing sarcoma cells. Although the expression of SPRY1 was low when compared with other tumors, SPRY1 was variably expressed in primary Ewing sarcoma tumors and higher expression levels were significantly associated with improved outcome in a large patient cohort. Taken together, our data indicate that EWS-FLI1-mediated repression of SPRY1 leads to unrestrained bFGF-induced cell proliferation, suggesting that targeting the FGFR/MAPK pathway can constitute a promising therapeutic approach for this devastating disease.

[HER2 testing in gastric cancer - results of a German expert meeting]. / HER2-Testung beim Magenkarzinom - Ergebnisse eines deutschen Expertentreffens.

Valid HER2 testing is essential for optimal therapy of patients with HER2 positive gastric cancer and the correct use of first-line treatment. While each breast cancer is routinely being tested for the HER2 status, HER2 testing in gastric cancer has still not become part of the routine and is often only done upon request by the therapist. An interdisciplinary German expert group took the challenges of HER2 testing in gastric cancer as an opportunity to address essential aspects and questions for the practical use of HER2 testing in this indication from the perspective of pathologists and therapists. The recommendations made in this manuscript reflect the consensus of all participants and correspond to their opinions and long-term experience.

[Predictive PD-L1 immunohistochemistry for non-small cell lung cancer : Current state of the art and experiences of the first German harmonization study]. / Prädiktive PD-L1-Immunhistochemie beim nichtkleinzelligen Bronchialkarzinom : Aktueller Stand und Erfahrungen der ersten deutschen Harmonisierungsstudie.

BACKGROUND: Antibodies against PD-1 and PD-L1 can cause strong and durable anti-tumor immune responses in non-small cell lung cancer (NSCLC). Immunohistochemistry for PD-L1 (PD-L1 IHC) was tested as a predictive biomarker. Several IHC assays and interpretation criteria were developed in parallel. AIM: The clinical significance of PD-L1 IHC in NSCLC and the optimum method for staining and interpretation of the results are the subject of ongoing studies. The diagnostic application of immunotherapy in NSCLC necessitates harmonization of PD-L1 IHC to obtain evidence for guidelines; therefore, a consensus opinion on a well-founded diagnostic mode of testing should be defined based on published studies and the results of the first German PD-L1 IHC harmonization study. METHODS: 1. Summary of the current data situation. 2. Evaluation of the first German PD-L1 IHC harmonization study (centralized, staining with PD-L1 IHC analogous to studies, 15 cases of NSCLC, 4 IHC study assays [28­8, 22C3, SP142 and SP263] and scoring by 9 pathologists). RESULTS: The use of PD-L1 IHC in NSCLC is suitable for identification of patients with an increased probability of a clinical benefit from immunotherapy. The various proportional cut-offs used to interpret the staining results can be summarized in a total score, which can be reproducibly assessed. The staining patterns of the four assays investigated were, however, not congruent in all situations. DISCUSSION: In principle, the use of PD-L1 IHC for assessment of the expression in tumor cells is a reliably determinable biomarker. Evaluation algorithms should be based on published clinical trials. For NSCLC approvals with obligatory PD-L1 IHC are to be expected but it remains to be seen to what extent PD-L1 IHC will be implemented in the clinical routine.

Outcome according to KRAS-, NRAS- and BRAF-mutation as well as KRAS mutation variants: pooled analysis of five randomized trials in metastatic colorectal cancer by the AIO colorectal cancer study group.

BACKGROUND: To explore the impact of KRAS, NRAS and BRAF mutations as well as KRAS mutation variants in patients with metastatic colorectal cancer (mCRC) receiving first-line therapy. PATIENTS AND METHODS: A total of 1239 patients from five randomized trials (FIRE-1, FIRE-3, AIOKRK0207, AIOKRK0604, RO91) were included into the analysis. Outcome was evaluated by the Kaplan-Meier method, log-rank tests and Cox models. RESULTS: In 664 tumors, no mutation was detected, 462 tumors were diagnosed with KRAS-, 39 patients with NRAS- and 74 patients with BRAF-mutation. Mutations in KRAS were associated with inferior progression-free survival (PFS) and overall survival (OS) [multivariate hazard ratio (HR) for PFS: 1.20 (1.02-1.42), P = 0.03; multivariate HR for OS: 1.41 (1.17-1.70), P < 0.001]. BRAF mutation was also associated with inferior PFS [multivariate HR: 2.19 (1.59-3.02), P < 0.001] and OS [multivariate HR: 2.99 (2.10-4.25), P < 0.001]. Among specific KRAS mutation variants, the KRAS G12C-variant (n = 28) correlated with inferior OS compared with unmutated tumors [multivariate HR 2.26 (1.25-4.1), P = 0.001]. A similar trend for OS was seen in the KRAS G13D-variant [n = 71, multivariate HR 1.46 (0.96-2.22), P = 0.10]. More frequent KRAS exon 2 variants like G12D [n = 152, multivariate HR 1.17 (0.86-1.6), P = 0.81] and G12V [n = 92, multivariate HR 1.27 (0.87-1.86), P = 0.57] did not have significant impact on OS. CONCLUSION: Mutations in KRAS and BRAF were associated with inferior PFS and OS of mCRC patients compared with patients with non-mutated tumors. KRAS exon 2 mutation variants were associated with heterogeneous outcome compared with unmutated tumors with KRAS G12C and G13D (trend) being associated with rather poor survival.